D10A is designed for a soft, wet, tacky track condition.
D20A is slightly tougher than the D10A and works well on crumbs or marbled tracks.
D30A is slightly tougher than the D20A and is designed for loose conditions or surfaces that clean off and become dry-slick.
The A40 is tougher than the D30A and is designed for drying track conditions that are transitioning and may lack overall grip (dusty, loose, sandy, etc.).
The 50 compound is designed for a hard packed track that forms a high grip racing groove.
The new FK tire is designed for larger oval kart tracks that require roll speed.

Every Hoosier race tire has a four character serial code embossed into ONE sidewall of the tire (example: J7B9). To be consistent when mounting from set to set, the tire should be placed on the rim so that the serial code faces towards the left side of the vehicle. This applies to tires without directional arrows. On tires with directional arrows, please mount the tire onto the rim so that the tire travels in the direction of the rotational arrow.

Once the tire is on the rim, we recommend placing the tire inside a mounting ring and adjusting the ring to fit snug around the tire. We highly advise using the mounting ring as we believe not using it can over stretch the carcass leading to inconsistent sizing. Never exceed 40 psi to seat beads. Once the tire has seated onto the rim, it is important the tire be initially stretched to about 10 psi over cold starting pressure to get the tire to its proper "profile". The tire should be set at this pressure for a few minutes and then dropped to the desired race pressure. The max inflation pressure is 57 psi (4.0 kg/cm2). Never exceed the max inflation pressure under any circumstance.